After grain is harvested it is often stored before processing. It is desirable to dry the grain before storage because the moisture content of the freshly harvested grain may cause the grain to spoil in storage. This practice has long been known and many systems have been designed to accomplish this task.
In many known designs heated air is passed through a column of grain contained within perforated walls. The particulars of these designs vary greatly from simplified single pass or single stage systems to more complex multipass or multistage systems. The known prior art dryers are generally effective at drying grain however some drawbacks have been associated with these designs.
Some of the simpler systems do not address the common problem of non-uniform drying of the grain. With only one uniform flow column the grain closest to the heated air source is scorched while the grain furthest from the heated air source remains moist.
The complex systems generally address the problem of non-uniform grain drying however the systems require more than one pass or stage and therefore generally include more components. Resultantly the systems are more expensive and may require more maintenance.
U.S. Pat. No. 4,423,557 to Westlaken describes a two pass gravity flow grain dryer having columns with perforated walls for passing hot air through the grain therein. There is described a dividing wall extending between the walls of the columns for dividing a portion of the columns into two channels, wherein each of the channels contains a discharging mechanism. The dividing wall is limited however in the sense that it is not perforated and it is restricted to not divide the perforated section of the column. This does not adequately ensure that the grain passing through the perforated section will discharge through the appropriate channel and thus ensure uniform drying.
A continuous flow type grain dryer which provides a generally uniform drying of the grain while remaining a simplified single pass design would be a useful invention.